Lay a piece of waxed paper, cling wrap or
polypropylene drop cloth material on the board to prevent the wing from
becoming glued to the board.
spar laid on the board will
determine how straight the wing is. If the spar is wavy, so will be
the wing and it can not be corrected. Be sure you understand
that. Getting this one piece properly aligned will go a long way
toward keeping the wing straight.
If this part is not straight then you can sand the leading edge and
trailing edge straight, but the airfoil will also be wavy and the
is not going to be thick enough to allow you to sand the wing to a uniform
shape across the span.
I lay a
straightedge on the board and then push the spar up against it. Pin
the spar in place and then remove the straight edge. If you use magnets
then hold the magnets that are already in place so they can not shift and put magnets on
the side where the straightedge was.
This is a very important step.
Do not rely on the plans to be straight because they probably are not.
Paper shrinks, expands and warps due to humidity.
This step was 4 minutes.